Influence of Microalloying and Isothermal Treatment on Microstructure and Mechanical Properties of High Carbon Steel

Indrajit Dey,Rajib Saha,Swarup Kumar Ghosh 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7

The influence of isothermal holding (IH) near the pearlite start temperature (Ps≈610 °C) and above the martensite starttemperature (Ms≈245 °C) were studied in two hot-rolled (FRT≈1000 °C) high carbon steels, without (HC0) and with Nbmicroalloying (HC1). Optical microscopy (OM), field emission scanning electron microscopy (FESEM) and high-resolutiontransmission electron microscopy (HRTEM) were utilised for observing the microstructural constituents whereas, nanoindentationand microindentation were performed to estimate the average hardness and elastic modulus values of various phaseconstituents. It has been observed that hot deformation in the austenite region results in the formation of a dual phase-typemicrostructure consisting of fine pearlite lamella and ferrite grains with some amount of degenerated pearlite. IH at 570 °Cleads to a higher volume percentage of ferrite and coarsening of pearlite whereas, IH at 300 °C results in mixed phases comprisingbainite, a very low amount of martensite/retained austenite (M/RA), pearlite and some amount of ferrite. Hot rolledmicroalloyed steel when isothermally held near the Psresults in a significant enhancement of ductility than hot rolled andair-cooled condition while sacrificing tensile strength marginally, which may be attributed to a higher percentage of ferriteand refinement of pearlite due to Nb addition. The estimated yield strength values correlate well with those experimentalyield strength values, but a little discrepancy has been noticed for the ultimate tensile strength values. Possible interpretationsare suggested in this paper.

Maximum Scour Depth at Piers in Armor-Beds

Rajkumar V. Raikar,Subhasish Dey 대한토목학회 2009 KSCE JOURNAL OF CIVIL ENGINEERING Vol.13 No.2

The paper presents a design method to determine the maximum equilibrium scour depth at piers embedded in a sand-bed overlain by a thin armor-layer of gravels using the experimental data of Dey and Raikar and those of Ettema. The proposed equation is in terms of empirical relationships, termed K-factors, which account for the effects of flow depth, pier shape, flow intensity, bed sediment size and armor gravel size on scour depth for individual cases of scour holes as identified by Dey and Raikar. These Kfactors are determined by fitting envelope curves to the experimental data. The estimated largest possible scour depths that can occur at circular and square piers with an armor-layer are 3.15 and 3.47 times the pier width, respectively. The paper presents a design method to determine the maximum equilibrium scour depth at piers embedded in a sand-bed overlain by a thin armor-layer of gravels using the experimental data of Dey and Raikar and those of Ettema. The proposed equation is in terms of empirical relationships, termed K-factors, which account for the effects of flow depth, pier shape, flow intensity, bed sediment size and armor gravel size on scour depth for individual cases of scour holes as identified by Dey and Raikar. These Kfactors are determined by fitting envelope curves to the experimental data. The estimated largest possible scour depths that can occur at circular and square piers with an armor-layer are 3.15 and 3.47 times the pier width, respectively.

Application of Multivariate Adaptive Regression Spline-Assisted Objective Function on Optimization of Heat Transfer Rate Around a Cylinder

Prasenjit Dey,Ajoy K. Das 한국원자력학회 2016 Nuclear Engineering and Technology Vol.48 No.6

The present study aims to predict the heat transfer characteristics around a square cylinderwith different corner radii using multivariate adaptive regression splines (MARS). Further, the MARS-generated objective function is optimized by particle swarm optimization. The data for the prediction are taken from the recently published article by thepresent authors [P. Dey, A. Sarkar, A.K. Das, Development of GEP and ANN model to predictthe unsteady forced convection over a cylinder, Neural Comput. Appl. (2015) 1-13]. Further,the MARS model is compared with artificial neural network and gene expression programming. It has been found that the MARS model is very efficient in predicting the heattransfer characteristics. It has also been found that MARS is more efficient than artificialneural network and gene expression programming in predicting the forced convectiondata, and also particle swarm optimization can efficiently optimize the heat transfer rate.

Nucleophilic Substitution Reactions of α-Chloroacetanilides with Pyridines in Dimethyl Sulfoxide

Dey, Shuchismita,Adhikary, Keshab Kumar,Kim, Chan-Kyung,Lee, Bon-Su,Lee, Hai-Whang Korean Chemical Society 2005 Bulletin of the Korean Chemical Society Vol.26 No.5

The kinetic studies of the reactions of $\alpha$-chloroacetanilides $(YC_6H_4NRC(=O)CH_2Cl;\;R=H\;(4)\;and\;CH_3$ (5)) with pyridines have been carried out in dimethyl sulfoxide at 95 ${^{\circ}C}$. The pyridinolysis rates are faster with 4 than with 5 whereas the aminolysis rates with benzylamines are faster with 5 than with 4. The Brønsted ${\beta}_X$ values are in the range from 0.30 to 0.32 and the cross-interaction constants, $\rho_{XY}$, are small negative values; $\rho_{XY}$ = -0.06 and -0.10 for 4 and 5, respectively. Based on these and other results, the pyridinolyses of $\alpha$-chloroacetanilides are proposed to proceed via a stepwise mechanism with rate-limiting addition of the nucleophile to the carbonyl group to form zwitterionic tetrahedral intermediate ($T^{\pm}$) followed by a bridged type transition state to expel the leaving group.

Coupled dynamic responses of a semisubmersible under the irregular wave and turbulent wind

Dey, Swarnadip,Saha, Kaushik,Acharya, Pooja,Roy, Shovan,Banik, Atul K. Techno-Press 2018 Ocean systems engineering Vol.8 No.4

A coupled dynamic analysis of a semisubmersible-type FOWT has been carried out in time domain under the combined action of irregular wave and turbulent wind represented respectively by JONSWAP spectrum and Kaimal spectrum. To account for the turbine-floater motion coupling in a more realistic way, the wind turbulence has been incorporated into the calculation of aerodynamic loads. The platform model was referred from the DeepCwind project and the turbine considered here was the NREL 5MW Baseline. To account for the operationality of the turbine, two different environmental conditions (operational and survival) have been considered and the aerodynamic effect of turbine-rotation on actual responses of the FOWT has been studied. Higher mean offsets in surge and pitch responses were obtained under the operational condition as compared to the survival condition. The mooring line tensions were also observed to be sensitive to the rotation of turbine due to the turbulence of wind and overestimated responses were found when the constant wind was considered in the analysis. Additionally, a special analysis case of sudden shutdown of the turbine has also been considered to study the swift modification of responses and tension in the mooring cables.

Weed Control by Herbicides and Fertilizers Applied Separately or Combined on Kentucky Bluegrass Lawn

Deying Li(다이엥 리),Kirk Howatt(컬크 호와트) 한국잡초학회·한국잔디학회 2007 Weed & Turfgrass Science Vol.21 No.1

잔디밭 관리 시 제초제와 비료의 혼합 처리는 시간절약 및 답압감소 등 여러 가지 장점이 있다. Weed & Feed는 제초제와 비료를 혼합 조제된 제품이다. 본 실험은 캔터키 블루그래스 잔디밭에서 비료 및 제초제를 단독으로 처리할 때와 Weed & Feed를 사용할 경우 그 효과를 비교하기 위해서 시작되었다. 실험에 사용한 Weed & Feed 28-3-3에는 세 가지 제초제 - 2,4-D 0.64%, MCPP 0.31% 및 dicamba 0.03%가 혼합 조제된 약제이다. 첫 번째 처리는 5월에 실시하였고, 두 번째 처리는 6월 또는 9월에 실시하였다. 단독으로 사용한 제초제는 2,4-D(LV-4, 4EC), MCPP(4EC) 및 dicamba(Clarity, 4EC)로 Weed & Feed의 50% 및 100% 수준으로 적용하였다. 실험기간 동안 우점 잡초는 민들레였으며, 제2 우점종은 2004년에는 엉컹키, 2005년에는 왕질경이로 나타났다. 실험결과 5월과 6월에 비료와 100% 수준의 제초제를 처리할 경우 수용할 수 있는 잔디밭 품질은 각각 112.3일과 83.7일 정도 유지되엇다. 하지만 Weed & Feed를 사용할 경우에는 각각 58.7일과 83.7일로 나타났다. Weed & Feed 효과는 사용 시기에 따라 차이는 있지만 비료와 50% 수준의 제초제를 처리한 것과 유사한 효과가 있는 것으로 나타났다. 잡초 방제 시 Weed & Feed에 비해 비료와 100% 수준의 제초제를 직접 처리하는 것은 Weed & Feed를 사용하는 그 이상의 효과가 있는 것으로 나타났다. Incorporating herbicides application into fertilization has several benefits including saving time and reducing traffics on the lawn. Premixed products of fertilizers and herbicides are commonly known as Weed & Feed in the lawn-care industry. To compare Weed & Feed with separate applications of fertilizers and herbicides on a Kentucky bluegrass (Poa pratensis L.) lawn, a Weed & Feed 28-3-3, containing 0.64% 2,4-D, 0.31% MCPP, and 0.03% dicamba of active ingredients, was used in this study. The first application was in May, with the second in June or Sept. Herbicides in forms of 2,4-D (LV-4, 4EC), MCPP (4EC), and dicamba (Clarity, 4EC) were applied at rates equal to the amounts in Weed & Feed or at half of the rates. The dominant weed in both locations was common dandelion (Taraxacum officinale Weber.) in 2005 and 2004. A secondary weed was Canada thistle (Cirsium arvense (L.) Scop.) in 2004 and broadleaf plantain (Plantago major L.) in 2005. When applied in May and June, fertilizer plus full rate of herbicides treatment achieved 112.3 and 83.7 days of acceptable turf quality in 2004 and 2005, respectively. During the same period, Weed & Feed resulted in 58.7 and 24.3 days of acceptable turf quality, respectively. Our study showed that Weed & Feed was generally as effective in weed control as the same amount of fertilizer plus half rates of herbicides sprayed although results may vary due to the timing of application. Fertilizer plus full rates of herbicides provided the same or better results of weed control than Weed & Feed.

Managing Mixtures of Tall Fescue (Festuca arundinacea Schreb) and Zoysiagrass (Zoysia japonica Steud.) for Athletic Turf

Deying Li(다이엥 리),Lei Han(레이 한) 한국잡초학회·한국잔디학회 2008 Weed & Turfgrass Science Vol.22 No.2

톨 페스큐와 한국들잔디의 혼합 조성은 미국의 전이지역에서 두 종간의 장점을 취하고 각종의 단점을 보완하는 실질적 관리기술로 제안되어 왔다. 이러한 두 종간의 초종 혼합은 관리 상 어려움이 있다. 본 연구의 목적은 한국들잔디와 톨 페스큐의 혼합이 운동장 답압 하에서 예초와 시비에 의해 적절한 수준의 잔디 관리가 가능한지 실험하였다. 한국들잔디는 1996년 6월에 파종하였고 동년 8월에 톨 페스큐를 덧파종하였다. 1996년 11월에 한국들잔디의 피복율은 질소시비수준 0, 50, 100㎏/㏊에서 62.36, 29.88, 30.02%를 나타내었다. 예고 6.5, 5, 3.S㎝에서 23.53, 41.95, 57.40%의 피복율을 보였다. 한국들잔디와 톨 페스큐의 혼합잔디는 1997년 7월에 1996년 늦가을과 큰 차이가 없는 피복율 수준을 보였다. 질소 시비율과 예고 간에는 유의한 수준의 교호작용이 있었다. 1998년 11월에는 한국들잔디의 피복율이 혼파 톨페스큐 두 품종간에 차이가 났는데,'Arid'와 'Grassland Garland' 조성구에서 각각 21.68%와 32.25%의 피복율을 보였다. 한국들잔디 피복율은 낮은 예고, 낮은 질소수준과 저답압에서 높은 경향을 보였다. 한국들잔디에서는 톨 페스쥬 품종간과 질소수준, 톨 페스큐 품종간과 예고, 답압정도와 질소수준에서 교호작용을 보였다. 한국들잔디의 줄기밀도는 1998년도 실험에서 예고 6.5, 5와 3.5㎝에서 7.42, 26.47과 58.96%를 나타내었고, 질소 수준 0, 50, 100㎏/㏊ 에서 47.26, 20.27, 26.26%의 밀도를 보였다. 한국들잔디의 밀도는 질소수준과 예고, 답압정도에서 영향을 받았는데 이것은 잔디 관리 방법에 따라 줄기밀도와 잎의 생장이 적응하는 방식이 다르다는 것을 의미한다. Managing a mixture of zoysiagrass with tall fescue has been proposed in transitional zone as a practical practice to combine the advantages of the two species and compensate the limitations. To manage the mixture is a challenge because two species are involved. The objective of this study was to determine if zoysiagrass/tall fescue mixture can be maintained with proper mowing and fertilization under simulated sport traffic at an acceptable quality level. Zoysiagrass was seeded in June and tall fescue was overseeded in August 1996. In November 1996, zoysiagrass coverage was 62.36, 29.88, and 30.02% for 0, 50, and 100 ㎏ ㏊<SUP>-1</SUP> N rates, respectively. At the same time, zoysiagrass coverage was 23.53, 41.95, and 57.40% for the mowing heights of 6.5, 5.0, and 3.5 ㎝, respectively. Zoysiagrass and tall fescue coverage in July 1997 was showing the same trend as in the late season of ] 996 although the differences were not as big. There were significant interactions between N fertilization rates and mowing heights. In November 1998, the zoysiagrass coverage was different among the two tall fescue variety mixtures, 21.68, and 32.25% in 'Arid' and 'Grasslands Garland', respectively. Zoysiagrass coverage was favored in lower mowing height, lower N rates, and lower traffic. Interaction effects on zoysiagrass were found between tall fescue variety and nitrogen rate, tall fescue variety and mowing height, and traffic and nitrogen rate. Zoysiagrass shoot density was 7.42, 25.47, and 58.95% for mowing heights of 6.5, 5, and 3.5 ㎝, respectively; and it was 47.27, 20.27, and 26.26% for N rates of 0, 50, and 100 ㎏ ㏊<SUP>-1</SUP>, respectively in 1998. The effects on zoysiagrass shoot density from the interaction of N rate and tall fescue variety was significant in 1998. Shoot density responded to the N rate, mowing height, and traffic differently from the ground coverage, indicating that shoot and leaf growth have different adaptation strategies.

Extraction of Exact Layer Thickness of Ultra-thin Gate Dielectrics in Nanoscaled CMOS under Strong Inversion

Dey, Munmun,Chattopadhyay, Sanatan The Institute of Electronics and Information Engin 2010 Journal of semiconductor technology and science Vol.10 No.2

The impact of surface quantization on device parameters of a Si metal oxide semiconductor (MOS) capacitor has been analyzed in the present work. Variation of conduction band bending, position of discrete energy states, variation of surface potential, and the variation of inversion carrier concentration at charge centroid have been analyzed for different gate voltages, substrate doping concentrations and oxide thicknesses. Oxide thickness calculated from the experimental C-V data of a MOS capacitor is different from the actual oxide thickness, since such data include the effect of surface quantization. A correction factor has been developed considering the effect of charge centroid in presence of surface quantization at strong inversion and it has been observed that the correction due to surface quantization is crucial for highly doped substrate with thinner gate oxide.

Hilbert series for moduli spaces of instantons on ℂ2/ℤ n

Dey, Anindya,Hanany, Amihay,Mekareeya, Noppadol,Rodrí,guez-Gó,mez, Diego,Seong, Rak-Kyeong Springer-Verlag 2014 Journal of high energy physics Vol.2014 No.1

Identification and Characterization of a Novel Antibacterial Peptide, Avian β-Defensin 2 from Ducks

Deying Ma,Ruiqin Wang,Wenyan Liao,Zongxi Han,Shengwang Liu 한국미생물학회 2009 The journal of microbiology Vol.47 No.5

In this study, a novel avian β-defensin (AvBD) was isolated from duck pancreas. The complete nucleotide sequence of the gene contained an 195 bp open reading frame encoding 64 amino acids. Homology, characterization and comparison of the gene with AvBD from other avian species confirmed that it was duck AvBD2. The mRNA expression of the gene was analyzed in 17 tissues from 21-day-old ducks. AvBD2 was highly expressed in the trachea, crop, heart, bone marrow, and pancreas; moderately expressed in the muscular stomach, small intestine, kidney, spleen, thymus, and bursa of Fabricius; and weakly expressed in skin. We produced and purified recombinant AvBD2 by expressing the gene in Escherichia coli. As expected, the recombinant peptide exhibited strong bactericidal properties against Bacillus cereus, Staphylococcus aureus, and Pasteurella multocida, and weak bactericidal properties against E. coli and Salmonella choleraesuis. In addition, the recombinant protein retained antimicrobial activity against S. aureus under different temperatures (range, -20°C to 100°C) and pH values (range, 3 to 12).